Migrate dependency management and packaging to poetry + dependencies version bumps

[nathanpainchaud]

This migration is motivated by recent breaking changes in how setuptools handle editable installs (see setuptools issues #3557, #3548).

These changes broke our workflow for projects depending on vital (i.e. shadowing of installed vital package by folder of the same name for the git submodule, install of hydra_plugins namespace package to make Hydra configs discoverable, etc.) , so investing the effort to migrate to a new packaging tool became worth it.

I like poetry personally because it centralizes the definition of dependencies, and it provides a good workflow for installing projects locally for development purposes (by default, package installed in editable mode with dev dependencies, etc.). At the same time, poetry also works with the intuitive pip install . when users just want to install the package as-is and are less interested by development concerns. This is just a quick overview, so I would suggest to either give a look at poetry's documentation or to message me directly if you have specific questions/concerns about how the workflows you're used to can be supported.

So, in the end, I would mostly ask you to review the setup instructions to make sure you're comfortable with them. You can also checkout the twin branch on the castor repo to see what changes the switch to poetry means for a project depending on vital.